The aims of this study are to: (1) evaluate the safety of orally administered pentoxifylline (PTX) in patients with HIV-associated Kaposi's sarcoma receiving concomitant antiretroviral therapy; (2) make an initial assessment of the pharmacokinetic interaction (if any) of PTX with antiretrovirals in patients with HIV-associated Kaposi's sarcoma; (3) evaluate the effects of PTX on selected immunologic and virologic parameters associated with HIV infection; and (4) assess the clinical activity of PTX in Kaposi's sarcoma.